In currently known machines of this type, the heat-sealing assembly includes a hot-blade device and a contrast element set transversely on opposite sides with respect to the web, and actuation means for controlling displacement of the heat-sealing assembly and mutual opening and closing between the hot-blade device and the contrast element in synchronism with advance of the web.
In these known machines, the heat-sealing assembly is traditionally mounted on a slide or a carriage, which can be translated with reciprocating rectilinear motion parallel to the direction of advance of the web.
This arrangement entails a sensible encumbrance that results in an overall longitudinal dimension of the machine that at times does not reconcile with the space available for its location of use.
Furthermore, the system of reciprocating rectilinear displacement of the heat-sealing assembly sets limits to the rate of advance of the continuous web, with consequent relatively modest production rates, and is generally complicated from the constructional standpoint and hence costly.